Details: Launch the new software installer in Eclipse (Help -> Install New Software...)
Add on the DTP repository site (click 'Add' and I installed from this site: Link: http://download.eclipse.org/datatools/updates/ and name it something like "DTP")
As I wanted the latest version of DTP so I selected the DTP 1.10.0 Extender SDK (Includes source and JavaDocs) If you want to see quickly what versions of DTP exist, go here: Link: http://eclipse.org/datatools/downloads.php as ZachM pointed to above.

You might also see the problem if you installed the version of Eclipse that comes packaged with the ADT bundle from the Android developer site. DavisRunning's answer for installing the database tools also helps in this case, except you might want to check with version of Eclipse you have. Mine was packaged with Juno so my download site was http://download.eclipse.org/releases/juno. After that just use the Amazon download site and the AWS toolkit should install as expected.